JPH0633753A - Exhaust emission control device for marine engine - Google Patents

Abstract

PURPOSE:To prevent an engine and an exhaust passage from being damaged by dividing the inside of an exhaust expansion chamber into two chambers by a partition, setting the chamber in the upstream to serve as the main expansion chamber and the chamber in the downstream to serve as the subexpansion chamber, and setting up an exhaust purifying catalyst in a connecting cylinder for connecting both the divided chambers. CONSTITUTION:An exhaust silencer 4 provided in an exhaust passage in the vicinity of an engine is formed into an inner/outer double wall structure by inner/outer shell members 11, 12. A water jacket 13 is formed between both the members 11, 12. The inside of the exhaust silencer 4 is divided into two chambers by a partition 21, to provide a main expansion chamber 22 in the upstream divided chamber and a subexpansion chamber 23 in the downstream divided chamber. Both the chambers 22, 23 are connected by a connecting cylinder 24 supported to the partition 21. An exhaust purifying honeycomb-shaped catalyst 25 is provided in the inside of the connecting cylinder 24. Exhaust discharged from the engine, before damped by air-flow resistance of the catalyst, is once expanded in the main expansion chamber 22, and thereafter to reach the catalyst, so that engine performance is prevented from worsening. A flow of air flowing in the catalyst is stabilized, and a purifying function is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for a marine engine, which is suitable for a small boat for play or competition.

[0002]

2. Description of the Related Art Conventionally, in this type of small marine engine,
As shown in FIG. 1 and FIG. 6, the outer shell of the exhaust silencer 4 has a double structure inside and outside to form a water jacket 13, and the engine 3
Cooling water is sent to the water jacket 13 to cool the silencer, and then the exhaust silencer 4 and the exhaust pipe 5
A method is adopted in which the cooling water is mixed with the exhaust gas at the connection part with, is guided to the propulsion device 2 through the exhaust pipe 5, and then discharged into the water.

On the other hand, a small boat equipped with this type of engine may capsize with the bottom of the ship facing up even with a slight operation error if it is subjected to an extreme driving operation, such as when it is used for competition. The boat itself is lightweight and can be easily restored, but seawater and lake water may flow back to the engine from the exhaust passage opened to the water during capsizing, so a backflow prevention device is provided in the exhaust passage. .

However, since the engine cooling water is discharged to the upstream side of the exhaust gas from the backflow prevention device, the engine cooling water may flow back to the exhaust port of the engine when the boat capsizes. In addition, even if the cooling water is combined on the downstream side of the exhaust from the backflow prevention device,
Although the conventional backflow prevention device prevents a large amount of water from flowing back, it is inferior in the ability to prevent a small amount of water from flowing back as fine particles.

In recent years, from the viewpoint of preventing air pollution, it has been considered to provide a catalyst for purifying exhaust gas in an exhaust passage even in a marine engine (for example, Japanese Patent Laid-Open No. 256868/1990).

[0006]

A catalyst for purifying exhaust gas is a ceramic carrier provided with a thin coating of the catalyst, and usually requires a considerably high temperature for activation, and the exhaust gas is exhausted during engine operation. 8 due to heat and oxidation reaction of unburned fuel components
Used at a high temperature of 00 ° C or higher. Therefore, if even a small amount of water, even a few drops, is refluxed from the backflow prevention device, the portion in contact with the water is rapidly cooled and is damaged by thermal shock.

[0007]

SUMMARY OF THE INVENTION In order to solve the problems described above, it is an object of the present invention to provide a device which can reliably prevent the engine cooling water from flowing back to the engine through the exhaust pipe even when the boat is capsized. According to claim 1, the exhaust expansion chamber provided in the exhaust passage in the vicinity of the engine has an inner and outer double wall structure, and the cooling water for the engine is provided in a water jacket formed between the double walls. In a marine engine that is sent and cooled, the inside of the exhaust expansion chamber is divided into two chambers by a partition wall, the upstream side is a main expansion chamber, and the downstream side is a sub-expansion chamber. It is characterized in that it is connected by a connecting cylinder that is supported by and is provided so as to project into both chambers, and that an exhaust gas purification catalyst is installed in the connecting cylinder.

According to the present invention, in the exhaust expansion chamber provided in the exhaust passage near the engine, the exhaust purification catalyst is provided, and the exhaust expansion chamber is connected to the exhaust expansion chamber by the connecting pipe below the exhaust expansion chamber. It is characterized in that a connected auxiliary expansion chamber is provided, and an auxiliary waterproof wall for a water reservoir surrounding the opening of the connecting pipe is provided upright in the auxiliary expansion chamber.

Further, according to claim 4, the exhaust expansion chamber provided in the exhaust passage near the engine has an inner and outer double wall structure, and the engine jacket cooling water is provided in a water jacket formed between the double walls. In a marine engine adapted to send and cool, an auxiliary expansion chamber connected to the exhaust expansion chamber by a connecting pipe is provided below the exhaust expansion chamber, and the connecting pipe and an exhaust pipe connected to the auxiliary expansion chamber are provided. While not arranging each other, an auxiliary waterproof wall for the water pool surrounding the opening of the connecting pipe is erected inside the auxiliary expansion chamber, and the drain port of the water jacket is located on the downstream side of the auxiliary expansion chamber. The point is that they are connected.

[0010]

The engine cooling water discharged from the engine flows through the water jacket provided in the exhaust expansion chamber to cool the exhaust expansion chamber. When the cooling water passes through the water jacket around the expansion chamber, it is connected to the exhaust passage on the downstream side of the auxiliary expansion chamber and is mixed with the exhaust gas to cool the exhaust gas and flow to the downstream side. When the boat capsizes, according to claim 1, the exhaust gas discharged from the engine is once expanded in the main expansion chamber and then reaches the catalyst before being attenuated by the ventilation resistance of the catalyst, so that there is no deterioration in engine performance. Moreover, since the pulsation of the exhaust pressure is attenuated, the airflow flowing through the catalyst becomes stable and the purification function thereof becomes stable. Further, the connecting cylinder supporting the catalyst is supported by the partition wall and is provided so as to project into the sub-expansion chamber, and since the opening is away from the wall surface forming the sub-expansion chamber, the water flowing backward is stored there, and the catalyst And the waterproof wall suspended on the front surface of the connecting cylinder as defined in claim 2 effectively prevents the cooling water that flows backward as fine droplets.

According to the third aspect, even if the cooling water once flowing into the exhaust passage flows back into the auxiliary expansion chamber, the auxiliary waterproof wall provided so as to surround the opening of the connecting pipe leads to the connecting pipe. Inflow, in other words, is prevented from flowing into the exhaust expansion chamber.

Further, according to the fourth aspect, the cooling water flowing back through the exhaust pipe is once blocked by the inner wall forming the auxiliary expansion chamber or the auxiliary waterproof wall for the water reservoir surrounding the opening of the connecting pipe, It is prevented that the auxiliary expansion chamber jumps directly from the exhaust pipe to the connecting pipe and flows backward.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, reference numeral 1 denotes a small boat utilizing the present invention, which includes a water jet propulsion type propulsion device 2. Three
Is an engine that drives the propulsion device 2. 4 is an exhaust silencer connected to the engine 3,
Is provided close to. Reference numeral 5 denotes an exhaust pipe, one end of which is connected to the exhaust silencer 4 and the other end of which is connected to the propulsion device 2. Reference numeral 6 denotes a backflow prevention device provided in the middle of the exhaust pipe 5, and when the boat 1 capsizes and the engine 3 goes below the exhaust pipe 5, seawater or lake water in the propulsion device 2 is exhausted from the exhaust pipe 5. This is a device for preventing backflow to the engine 3 through the. Reference numeral 7 denotes a rod-shaped operation handle that swings the propulsion device 2 to the left and right to change the traveling direction. The backflow prevention device 6 has a known configuration, and detailed description thereof will be omitted.

The exhaust silencer 4 is, as shown in FIGS. 2 and 3,
The inner shell member 11 and the outer shell member 12 form a double wall inside and outside, and a water jacket 13 is provided between the members 11 and 12.
Has become. The exhaust silencer 4 is connected to an exhaust collecting pipe 15 of the engine via a U-shaped pipe 14. Reference numeral 15a is an exhaust port of the engine connected to the exhaust collecting pipe 15. The U-shaped pipe 14 and the exhaust collecting pipe 15 have a double structure of an inner wall and an outer wall similarly to the exhaust silencer 4, and an annular cooling water connected to an exhaust passage of the cooling water of the engine is provided between both walls. It forms the passage 16. The exhaust silencer 4 is cooled in this way,
The exhaust gas passing through the interior is cooled and contracted to reduce the noise level and the ventilation resistance.

In the exhaust silencer 4, the inner surface of the inner shell member 11 serves as an exhaust expansion chamber, which is divided into two chambers by the partition walls 21 and 21, and the upstream chamber forms the main expansion chamber 22 and the downstream chamber. The chamber constitutes the sub expansion chamber 23. The two chambers 22 and 23 are communicated with each other by a connecting cylinder 24 supported by the partition wall 21. Further, a honeycomb-shaped catalyst 25 for purifying exhaust gas is provided inside the connecting cylinder 24.

Therefore, the high-temperature exhaust gas discharged from the exhaust port 17 of the engine 3 into the exhaust collecting pipe 15 flows into the exhaust silencer 4 through the U-shaped pipe 14 and is primarily expanded in the main expansion chamber 22. After that, it is once throttled by the connecting cylinder 24 and again expands to flow into the auxiliary expansion chamber 23. Since the exhaust gas contains an unburned fuel component and a small amount of oxygen, when passing through the catalyst 25, an oxidation reaction occurs to reduce the unburned fuel component. At that time, the catalyst 25
Since the connecting tube 24 supporting the is heated to a high temperature, stainless steel which is a heat resistant material is used. The other portion forming the inner shell member 11 is cooled by cooling water and does not reach a high temperature, so that castable aluminum or mild steel having good press workability is used.

Reference numeral 26 indicated by a chain double-dashed line is a waterproof wall welded above the inner surface of the auxiliary expansion chamber 23. If the boat 1 is capsized, engine cooling water may flow back into the auxiliary expansion chamber 23. However, the cooling water does not reach the connecting cylinder 24 having the catalyst 25.

The sub-expansion chamber 23 is further connected via a connecting pipe 31 to an auxiliary expansion chamber 32 provided below. Similarly to the exhaust silencer 4 and the like, the auxiliary expansion chamber 32 is also formed as an inner and outer double wall by an outer wall member and an inner wall member, and a cooling water passage 16 is formed between them. Reference numeral 33 denotes an auxiliary waterproof wall, which connects the exhaust pipe 5 and the connecting pipe 31 connected to the auxiliary expansion chamber 32.
It is provided so as to partition the space between.

Here, the connecting pipe 31 and the exhaust pipe 5 are arranged so as not to face each other, and the cooling water passage 16 is provided.
The downstream end of is open into the exhaust pipe 5. Connection pipe 31
Is not directed toward the exhaust pipe 5, and the exhaust pipe 5 is also connected to the connecting pipe 31.
It is opened avoiding the direction. Therefore, the cooling water passage 1
Even if the cooling water flowing from 6 into the exhaust pipe 5 flows back into the auxiliary expansion chamber 32 due to the overturning of the boat 1, it does not jump from the exhaust pipe 5 into the connecting pipe 31 at a stretch. Further, in this embodiment, in order to more surely prevent the backflow of the cooling water, an auxiliary waterproof wall 33 for water storage is provided upright around the opening of the connecting pipe 31 in the auxiliary expansion chamber 32.

It should be noted that the provision of the auxiliary waterproof wall 33 is not essential in the structure of the invention, and the connecting pipe 31 may simply be provided so as to slightly project into the auxiliary expansion chamber 32. Further, in place of the auxiliary waterproof wall 33 or together with the auxiliary waterproof wall 33, it is also effective to provide a check valve device 34 in the downstream opening of the connecting pipe 31 for preventing the backflow of the cooling water. In this example, the check valve device 34 includes a weight 35, and the check valve device 34 is closed by the weight of the weight 35 at the same time when the boat 1 is overturned.

Since this embodiment is constructed as described above, when the boat 1 is capsized, the cooling water in the exhaust pipe 5 flows back into the auxiliary expansion chamber 32 as shown in FIG. It is blocked by the wall 33 and accumulates on the downstream side (a). Even if some cooling water may exceed the auxiliary waterproof wall 33 for some reason, the connecting pipe 31 protruding into the auxiliary expansion chamber 32
You can't go in and collect around it (b). In addition,
In the case of FIG. 3, the auxiliary waterproof wall 33 is not provided, and the backflow is blocked by the connecting pipe 31 protruding into the auxiliary expansion chamber 32. Even if some of the cooling water enters the connecting pipe 31 for some reason, the check valve device 34 provided at the downstream end of the connecting pipe 31 prevents further backflow. In this way, the means for preventing at least backflow is constructed in two stages in the auxiliary expansion chamber 32. Therefore, even when the boat 1 capsizes, even if the cooling water in the exhaust pipe 5 flows back into the auxiliary expansion chamber 32 or the auxiliary expansion chamber 23, it does not reach the engine 3 or the catalyst 25. And prevent them from being damaged.

[0022]

As described above, according to the present invention, the exhaust gas discharged from the engine is temporarily expanded in the main expansion chamber before being attenuated by the catalyst before being attenuated by the ventilation resistance of the catalyst. There is no deterioration in engine performance. Also,
The airflow flowing through the catalyst is stable and the purification function is stable. Further, since the connecting cylinder supporting the catalyst is supported by the partition wall and is provided so as to project into the sub-expansion chamber, and the opening is away from the wall surface forming the sub-expansion chamber, the water that flows backward is stored therein, With the waterproof wall hung on the front surface of the connecting cylinder as defined in Item 2, there is an effect of preventing the catalyst from reaching.

Further, according to claim 3, even if there is water that flows back through the conventional backflow prevention device,
The auxiliary waterproof wall provided in the auxiliary expansion chamber immediately before the catalyst has an effect of preventing the auxiliary waterproof wall from flowing into the exhaust expansion chamber through the connecting pipe.

Further, according to the fourth aspect, the cooling water flowing back through the exhaust pipe is once blocked by the inner wall forming the auxiliary expansion chamber or the auxiliary waterproof wall for a water reservoir surrounding the opening of the connecting pipe, In the auxiliary expansion chamber, it is prevented that the exhaust pipe directly jumps into the connecting pipe and backflows, thereby preventing the backflowed water from reaching the catalyst.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a small boat embodying the present invention.

FIG. 2 is a vertical cross-sectional view taken along the exhaust pipe.

FIG. 3 is a longitudinal sectional view corresponding to FIG. 2 showing another embodiment.

FIG. 4 is a longitudinal sectional view corresponding to FIG. 2 showing a state in which the boat is capsized.

5 is a vertical cross-sectional view corresponding to FIG. 3 showing a state in which the boat is capsized.

FIG. 6 is a vertical sectional view corresponding to FIG. 2 showing a conventional exhaust expansion chamber.

[Explanation of symbols]

 6 ...- Backflow prevention device 13 ... Water jacket 16 ... Cooling water passage 21 ... Partition wall 22 ... Main expansion chamber 23 ... Sub expansion chamber 24 ... Connection cylinder 25 ... Catalyst 26 ... Waterproof wall 31 ... Connection pipe 32 ... Auxiliary expansion chamber 33 ... Auxiliary waterproof wall

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F01N 7/12 F02B 67/00 F 7541-3G

Claims (4)

[Claims] 1. An exhaust expansion chamber provided in an exhaust passage near an engine has an inner-outer double wall structure, and cooling water for the engine is sent to a water jacket formed between the double walls for cooling. In a marine engine, the inside of the exhaust expansion chamber is partitioned into two chambers by a partition wall, and the upstream side is the main expansion chamber, and
A marine engine in which the downstream side is formed as a sub-expansion chamber, and the space between the two chambers is connected by a connecting cylinder that is provided so as to project into both chambers and an exhaust gas purification catalyst is installed in the connecting cylinder. Exhaust purification device. 2. The exhaust gas purification device for a marine engine according to claim 1, wherein a waterproof wall is provided above the inner surface of the auxiliary expansion chamber and is suspended from the front surface of the connecting cylinder. 3. An exhaust expansion chamber provided in an exhaust passage near an engine, wherein an exhaust purification catalyst is provided, and an auxiliary expansion connected to the exhaust expansion chamber by a connecting pipe below the exhaust expansion chamber. An exhaust gas purification device for a marine engine, which is provided with a chamber, and an auxiliary waterproof wall for a water pool that surrounds the opening of the connecting pipe is erected inside the auxiliary expansion chamber. 4. An exhaust expansion chamber provided in an exhaust passage near the engine has an inner and outer double wall structure, and cooling water for the engine is sent to a water jacket formed between the double walls for cooling. In a marine engine, an auxiliary expansion chamber connected to the exhaust expansion chamber by a connecting pipe is provided below the exhaust expansion chamber, and the connecting pipe and the exhaust pipe connected to the auxiliary expansion chamber do not face each other. An auxiliary waterproof wall for a water reservoir surrounding the opening of the connecting pipe is erected in the auxiliary expansion chamber, and the drain port of the water jacket is connected to the downstream side of the auxiliary expansion chamber. Exhaust purification device.